Microhabitat Preferences and Movements of the Weatherfish, Misgurnus fossilis, in a Drainage Channel

Abstract

Habitat preferences and movements of the weatherfish, Misgurnus fossilis, were studied in a drainage channel of the lower River Havel region (Saxony-Anhalt) from July to November 1995. During summer, adult fish preferred dense vegetation patches (e.g. Elodea canadensis) whereas juveniles preferred the reed zones along the bank lines, characterized by coarse detritus and extremely shallow water depths (<0.1 m). All size groups totally avoided open substratum without vegetation structures. In total, 166 weatherfish ≥ 14 cm were marked individually by injected dyes and their movements were documented by recaptures (recapture rate 29%). Most of the weatherfish showed stationary behaviour or site constancy. The majority of fish (70.1%) were recaptured within ranges of 50 m with reference to the first release point. The mean movement distances slightly increased during the search for overwintering habitats in the first weeks of October. Weatherfish stocks in drainage channels of the study area are strongly affected by annual machine weeding due to depletion of suitable microhabitats and direct removal of fish. Alternative maintenance protocols for drainage channels and ditches are proposed.